For now I'm just going to have the callback URL trigger a pull of the authoritative feed, rather than actually using the delivered content. Mostly because FeedOnFeeds' architecture is a bit crufty in that regard, but also it makes the security/validation side of things easier (even if it does end up wasting some bandwidth in the end).
Yay, my fork of FeedOnFeeds supports WebSub! http://github.com/fluffy-critter/Feed-On-Feeds
I've also submitted a PR to upstream, so hopefully everyone gets it soon.
Also while testing this I ended up moving to my own hosted hub at SuperFeedr.com and discovered that there are a bunch of other readers out there that support it too!
Well, I don't know about "a bunch" but so far https://theoldreader.com definitely does.
The following sites seem to give you WebSub support for free:
• feedburner.com (although presumably that's push notifications on top of their own pull, so not REALLY push)
• self-hosted WordPress (with the PuSHpress extension) - bonus for being built-in to the CMS!
And of course you can add it (and Webmention) to any RSS or Atom feed using Pushl. ;) http://github.com/fluffy-critter/Pushl
Anyway WebSub gives you the reliability of pull and the efficiency of push, and unlike ActivityPub you can easily switch hubs with absolutely no disruption to your readers.
Subscribers who are still pointed at my old site’s feeds are still getting updates and receiving WebSub notifications. RSS et al have a *migration path*. ActivityPub doesn’t even have that on its radar.
I could change domains if I wanted to and my readers would follow me as long as I get the right path redirections in place.
When I switched from MovableType to Publ my entire URL scheme changed and my feed protocol changed from RSS to Atom. I bet nobody even noticed, aside from a momentary blip of reposted content (because it wasn’t worth mapping the URNs - but I could have if I really wanted to!)
If my WebSub hub goes down I change one value in one template file and everyone will migrate to the new one with no disruption at all, aside from some notifications being slightly delayed between poll intervals.
And this isn’t just theoretical, this is tested and working. Just as a side effect of my tinkering today. It took no effort on my part or anyone else’s.
meanwhile, I posted my blog entry about WebSub, IFTTT pretty much immediately saw the update (via polling, ironically - IFTTT doesn't seem to support WebSub!) and reposted it to Twitter, and then the Mastodon crossposter took....... 37 minutes to repost it here. (I have since deleted it.)
yeah activitypub sure is working for immediate updates, huh
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